Introduction
Secondary hemophagocytic lymphohistiocytosis (SHLH) without familial history or known genetic predisposition is considered an overwhelming and life-threatening systemic inflammatory syndrome. SHLH can be related to infectious diseases (IAHS), associated with autoimmune diseases (MAS), or due to malignancies (M-HLH). Over half of all the SHLH cases culminate in multiple organ failure, with up to 86% requiring admission to the intensive care unit (ICU). Among ICU patients, SHLH are usually triggered by infection disease and sepsis[1].
Appling initial chemotherapy including etoposide combined with steroids and cyclosporine A in a timely fashion is important for survival. However, despite advances and improvements in chemotherapy, in 20% of cases, SHLH patients do not respond to conventional treatment, many of these patients die of rapid deterioration due to severe sepsis and MODS[2]. The mortality rate in SHLH with MODS patients has remained unacceptably high, at greater than 50% in some studies[3]. In children, SHLH may present with more acute fulminant manifestations and the incidence of MODS was higher than adults[4,5]. Poor outcomes in children with SHLH-associated MODS have led to a call for action to improve early diagnosis, institute new preventive measures, and develop new treatments to improve clinical outcomes.
Recently, Continuous renal replacement therapy (CRRT) has evolved from standard renal replacement therapy into an especially unique role in “mutiple-organ support technology” for MODS patients. CRRT is very effective in removal of inflammatory mediators, as well as maintaining fluid balance and hemodynamic stability for critical ill patients[6]. Aggressive application of CRRT was found to decrease mortality in adult patients with septic shock and MODS[7]. SHLH patients may need CRRT for renal replacement, inflammatory mediator or cytokine removal. Similarly, CRRT is an important treatment for severe SHLH patients, although there are insufficient studies regarding the efficacy and indications for CRRT in the pediatric HLH ICU population. We previously found that high-volume hemofiltration may improve organ function by decreasing tumor necrosis factor-α and interleukin-6, which might be an effective adjunctive treatment in secondary hemophagocytic lymphohistiocytosis[8]. The mortality among children with MODS requiring CRRT continues to be very high. Therefore, it is important for physicians to identify patients in whom aggressive treatment may offer recovery or those who may benefit from CRRT.
To the best of our knowledge, there are no available data on outcomes of critically ill children with SHLH and MODS receiving CRRT and identifying relevant prognostic factors. In this study, we initially analyzed survival outcomes among 52 pediatric patients with SHLH and MODS receiving CRRT. Then we assessed predictive factors for survival outcome. PRISM scores were used to assess whether the observed effect was independent of severity of illness.